Note that the shortcut "age" is a default shortcut in E-SURGE (see table 5 in E-SURGE manual), so I would recommend to change the name of your shortcut (Bage for banding/marking age).Then, set the number of age-classes to 3 (it will avoid unnecessary huge age matrix).I would also recommend to verify your current shortcut to create separate shortcut for each age-class to be sure that your shortcut really does what you want:Juv = g(1).a(1)Sub = g(1).a(2)&g(2).a(1)Ad = g(1).a(3)&g(2).a(2:3)&g(3)

Then, try (Juv+Sub+Ad).[i+t*x(1)]You need to give t*x(1) to say that the covariate vary with time.